@Maxpm, there's a chance my question was subconsciously inspired by that. (I think programmers have a problem between the illogicality of having unmatched parentheses, and the illogicality of using the closing parenthesis 'twice' :)[)]
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BenjolFeb 3 '11 at 14:35

8 Answers
8

It is acceptable, but you should use it with care. Generally, you should avoid having long texts in parentheses, as the reader will eventually forget that he is inside a parentheses block.

In serious papers and letters, you should avoid it completely, and rather find a way of re-phrase it.

In conversational e-mails, blog posts, StackExchange posts etc. it might be more natural to use it, but the inner parenthesis should never be long (just a couple of words). The most important is to make sure that the reader don't get confused of where the parenthesis start and end.

Example

With nested parentheses

This is a quick example on how to rephrase a potential problematic use of nested
parenthesis.
(It can be a less important section like this (which is quite long, even if it is not important), and when you continue, the reader might be lost in where in the parenthesized text he is, and might wonder if he still is inside any parentheses.)
Anyway, the main text continues here.

Re-phrased to remove nesting

This is a quick example on how to rephrase a potential problematic use of nested parenthesis.

(It can be a less important section like this. It is quite long, even if it is not important. Now when you continue, the reader is not lost anymore because the long section is taken out in a separate paragraph, and no inner parentheses can be mistaken for an early termination of the outer section.)

Can you give links (or references) with examples of nested brackets? Even better with different types of nested brackets...
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Gennady Vanin Геннадий ВанинFeb 15 '11 at 17:22

4

"In conversational e-mails, blog posts, StackExchange posts etc. it might be more appropriate to use it, but the inner parenthesis should never be long (just a couple of words)." Unless you are answering a question on Stack Overflow that is about Lisp.
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райтфолдDec 3 '11 at 12:24

I've found that with too many parentheses, it can be hard to make sure each is matched without a text editor or compiler that detects syntax errors (like a programming IDE)
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T. WebsterMay 12 '12 at 1:20

@T.Webster: Yes, that is exactly why you should use it with care as I said in my answer. A good advice would be to look quickly over what you have written, and see if it is easy to spot the matched parenthese pairs (without the aid of a programming IDE...).
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aweMay 15 '12 at 7:41

You are supposed to use square brackets for internal parens, if you must use them. You are not supposed to nest parens themselves.
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tchristSep 4 '12 at 4:08

True. Even single brackets are usually a thing to avoid in full prose, like novels or complicated, abstract texts: they are most of the time neither pleasant to the eye of the reader nor easy on his mind. Of course there are plenty of situations where they are fine, though.
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CerberusFeb 3 '11 at 3:08

4

@Brad: 'single' = single; 'brackets' = parentheses. :-) "Parentheses" is the American name for what is elsewhere just called "bracket". What Americans call "bracket" is called "square bracket" elsewhere.
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ShreevatsaRFeb 3 '11 at 5:54

3

Usually when I notice myself in the need to use two pairs of nested parentheses (or generally when overusing them), I edit the whole sentence so at least my outer parentheses-content is part of the actual text.
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pokeFeb 3 '11 at 8:46

3

@ShreevatsaR: This is one of the few places where I feel American English has a better approach. In computing it is entirely necessary to differentiate with ease and I find myself having to train juniors to say parentheses, brackets, braces, chevrons, guillemets (ok, they never say this "double angle bracket" persists).
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OrblingFeb 3 '11 at 11:05

5

@Orbling: Round bracket? Though generally I am of the parentheses, square bracket, curly brace camp; bracket is just such a nice square word, and brace so deliciously curly.
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Jon PurdyFeb 3 '11 at 13:16

Nesting parentheses should be done with square brackets "([ ])". But since square brackets are usually used for citations, this is confusing. The answer is to eliminate all nested parentheses by appropriate rewording. (Dashes, otherwise not recommended, can have a use here.)

@Orbling: Yes, though after I started programming I rankled under the restriction. Why not have subgroups set off by extra parens? But the point is, code and mathematical expressions are usually set off with whitespace to be readable, and a good IDE will show you the opening brace when you put the cursor next to the closing brace, etc. Writing is not coding, although sometimes I wish it could be that precise.
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RobustoFeb 3 '11 at 11:55

Aye, I certainly sympathise with that view. Though the great beauty of English is in the myriad of meanings that can be formed from the simplest of constructions.
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OrblingFeb 3 '11 at 12:33

The copyeditor on the last edition of one of my books changed the two instances of nested parens into parens on the outside and square brackets on the inside. It’s formally correct, but not what a programmer would necessarily think to od.
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tchristSep 4 '12 at 4:10

@Brad Cupit: Well, they can be. But technically they have specific uses, e.g. square brackets are usually used for editorial comments or amendments, annotations, though these uses are not absolute. Read through this article for a full explanation, en.wikipedia.org/wiki/Bracket
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OrblingFeb 3 '11 at 1:47

1

Very good answer. Using different kinds of parenthetical markers can work, though not in editions of manuscripts etc, where each marker has its own function.
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CerberusFeb 3 '11 at 2:32

2

Let us all nest parentheses (brackets, whatever), please. The more we do this, the more it becomes standard English.
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H2ONaClFeb 3 '11 at 8:35

1

@DavidHeffernan - Sure. () alter the order of operations. Like ( 2 + 3 ) x 4, whch is 20, but without the parentheses would be 14. () also denotes an open interval - that is, (0,1) is the set of real numbers greater than 0 but less than 1. [] denotes a closed interval, so [0,1] means all the real numbers not less than 0, and not greater than 1. [] is also sometimes used for the floor function, but that's becoming less and less common. {} denotes a set, either with the elements listed or described - for example { 0, 1, 2 } or { all even numbers }. And yes, I do have a degree in mathematics.
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user16269Feb 7 '12 at 11:06

1

@DavidWallace On my desk at the moment, I have a Springer volume titled, An Introduction to Statistical Modeling of Extreme Values by Stuart Coles. The page it coincidentally happens to be turned to has an expression exp{-[1+xi({z-u}/sigma)]^-1/xi} for the GPD distribution. It may not be the norm in your area of maths but there are plenty of subject areas in maths where it is the norm. I suggest you write to Springer to put them right!!
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David HeffernanFeb 7 '12 at 20:03

I have found that people who appreciate stressing thoroughly the logical construction of their sentences to make them totally unambiguous tend to use parentheses a lot, and to nest them, even though (see other answers) it's considered poor form. In particular, scientists (especially mathematicians and logicians) seem to do that more commonly than other people.

In looking at this question, I was immediately reminded of the work of William Faulkner, an undoubtedly well-known author in the United States. He is notorious for his complex sentences that can go on for pages. In some of them, he unapologetically uses nested parentheses.

While Faulkner sets a precedent doing this, it is not at all proof of the 'correct' usage. His motivation is quite different. I like the way Louis Rubin puts it in his essayThe Dixie Special: William Faulkner and the Southern Literary Renascence:

His very style itself, with the long sentences, the liberal deployment of adjectives, the parentheses, and the parentheses within parentheses, proceeds from the conviction that reality can be represented only when presented in its full complexity, leaving out nothing that is important. His admiration for Thomas Wolfe, he said on several occasions, was for that novelist's attempt, however impossible of fulfillment, to put all experience on the head of a pin.

I bring Faulkner's example up for the sake of introducing a different angle on the OP's question. It may not be the best choice stylistically to nest parentheses, but there have been literary precedents that show the practice. The example of Faulkner's usage of the nested parentheses shows that there is a purpose in his writing to convey a sense of complexity and to leave nothing out.

Parentheses are a way to stuff more ideas into a sentence than it could otherwise bear. They make life easier for the writer who is trying to capture all his ideas as they bubble up, but harder for the reader trying to make sense of it all. If you nest your parentheses, you risk losing your reader entirely.

So I'd say, in your first draft, go ahead and use as many parentheses as you want, but in later drafts you should try to eliminate them — especially the nested ones.

I think, it is acceptable. If you really being the author need it for addressing your readers, as you know them. And do you really know them?

But now who would limit himself to these a bit old brackets, parenthesis and so on, when you can use excellently old-fashioned, even coming from the times of handwrited books, changing of the size and form of the text itself.

As for paper text, your possibilities nowadays have really no no no no boundaries.

As for tagged text, as here, you have not so many possibilities, but
you can put or leave the additional info in the other place and leave so your main text

clean.

Now, as the text is edited, if you need some of these tricks, you can follow the ling that is connected to the time of edition and on the revisions page choose to look the source or markdown (such button <>).